Staling of baked products (such as bread) has been recognized as a problem which becomes more serious as more time lies between the moment of preparation of the bread product and the moment of consumption. The term staling is used to describe changes undesirable to the consumer in the properties of the bread product after leaving the oven, such as an increase of the firmness of the crumb, a decrease of the elasticity of the crumb, and changes in the crust, which becomes tough and leathery.
The firmness of the bread crumb increases further during storage up to a level, which is considered as negative. The increase in crumb firmness, which is considered as the most important aspect of staling, is recognized by the consumer a long time before the bread product has otherwise become unsuitable for consumption
The prior art suggests to retard the staling by the addition to the dough of various amylases, such as glucoamylase (amyloglucosidase) which hydrolyzes starch to form glucose (G1); soybean beta-amylase which hydrolyzes starch to form maltose (G2); alpha-amylase which hydrolyzes starch in an endo manner; or pullulanase which hydrolyzes alpha-1,6 bonds in an endo manner. WO 91/04669 discloses the use of a maltogenic amylase from B. stearothermophilus to retard staling.
The enzyme is commercially available from Novo Nordisk A/S under the tradename Novamyl.RTM.. U.S. 5,698,245 discloses the use of certain maltotriose-forming enzymes to improve the quality of bread, including the prevention of bread solidification, particularly when frozen dough is used.